Laminate based on epoxy resin for printed circuits

Abstract

A laminate based on epoxy resin for printed circuits has epoxy resin-impregnated outer plies, each containing a substrate of glass fibers and epoxy resin-impregnated core plies, each containing a flat textile form or construction made of synthetic thermoplastic fibers.

What is claimed is: 
     
       1. A laminate based on epoxy resin for preparation of printed circuits, which comprises a multilayered composite having epoxy resin-impregnated, outer plies containing a substrate of glass fibers and at least one epoxy resin-impregnated core ply containing a flat textile form of synthetic thermoplastic fibers, each substrate containing glass fibers having a weight per unit area of 70-350 g/m 2  and each flat textile form containing synthetic thermoplastic fibers having a weight per unit area of about 100-400 g/m 2  ; said composite having a dielectric constant ε.sub.τ at 20° C. and 16 6  Hz of smaller than 5, a dissipation factor tan δ at 20° C. and 10 6  Hz of smaller than 0.05, and a water absorption when stored in cold water according to DIN 53 472 of smaller than 30 mg/4 d; the outer plies containing a substrate of glass fibers having an epoxy resin content of about 40 to 65% by weight and the at least one core ply containing a flat textile form having an epoxy resin content of about 45-85% by weight. 
     
     
       2. A laminate according to claim 1, wherein the flat textile form contains fibers of linear, saturated polyesters and/or copolyesters comprising polybutylene terephthalate, poly-1,6-cyclohexylene dimethyl terephthalate, polyethylene terephthalate, polyethylene terephthalateadipate and/or polybutylene terephthalate-adipate. 
     
     
       3. A laminate according to claim 1, wherein the flat textile form contains fibers of polyimide. 
     
     
       4. A laminate according to claim 1, wherin the flat textile form contains fibers of polyacrylonitrile and/or styrene-acrylonitrile. 
     
     
       5. A laminate according to claim 1, wherein the flat textile form contains fibers of polysulfone, polyether sulfone, polyacrylic ether, polyphenylene sulfide, modified polyphenylene oxide and/or polyparahydroxybenzoate. 
     
     
       6. A laminate according to claim 1, wherein the flat textile form contains fibers of polyoxymethylene of polycarbonate. 
     
     
       7. A laminate according to claim 1, wherein, respectively, one outer ply with a substrate of woven glass fiber fabric and/or nonwoven glass fiber fabric and/or glass fiber mat is arranged on the topside and on the underside of said composite. 
     
     
       8. A laminate according to claim 1, wherein, respectively, two outer plies with a substrate of woven glass fiber fabric and/or nonwoven glass fiber fabric and/or glass fiber mat are arranged on the topside and on the underside of the composite. 
     
     
       9. A laminate according to claim 1, wherein said composite exhibits a dielectric constant ε.sub.τ at 10 6  Hz and 20° C. of smaller than 5, preferably smaller than 4.0. 
     
     
       10. A laminate according to claim 1, wherein a conductive metallic foil is bonded to at least one of the outer glass fiber plies of said composite. 
     
     
       11. A laminate according to claim 1, wherein the composite has a plurality of core plies containing the synthetic fibers in an amount between 2 to 15. 
     
     
       12. A laminate according to claim 1, wherein the weight ratio of the at least one core ply of synthetic fibers to the outer plies of the glass fibers lies between 0.5 and 6.